Comments

It is possible, they go from the Atlas mountains about one hours drive from Marrakech and start very early in the day.
The main operator Cieldafrique has information which will serve as guidance only.
I don't know of other operators but perhaps a visit to the Tourist Info office will be more revealing or enquire at the hotel.
I was very disappointed at the extraordinary costs as I had hoped to do this myself: 2050Dh which equates to 180/£160.
I have seen other operators in the recent past offering this at just over 100.
http://www.cieldafrique.info/anglais/accueil.php for information only.